1. Technical Field
The present invention relates to a portable device for rehabilitating an impaired user having difficulties in executing simultaneous reaching and lifting tasks. The device is in particular suitable for use in rehabilitation and/or physical therapy programs for the treatment of neuro-vascular or musculoskeletal injuries or diseases of the upper limb.
2. Description of Related Art
Hundreds of thousand of people are disabled each year because of upper limb motor impairments. Impairment can be due to neurological diseases such as stroke (see for example the ‘Heart disease and stroke statistics 2007’ published by the American Heart association and American stroke association), or can be due to musculoskeletal injuries. In both cases the disease can result in a decreased range of motion, muscular weakness, loss of speed and/or reduced coordination of the affected limb.
Physical therapy is known to be effective in reducing the degree of disability (Nancy Byl et al., Neurorehabilitation and Neural Repair, Vol. 17, No. 3, 176-191 (2003); Darlene Hertling, Lippincott Williams and Wilkins publishing, 2005). Recently published research work (Liesbet De Wit et al., Stroke. 2007; 38; 2101) confirm that better results in term of rehabilitation outcome are obtained in those care centers where patients receive more therapy per day for extended periods of time. Physical therapy is currently administered in hospital or specialized care-centers only. A physical therapist leads the patient trough a series of repetitive exercises during training sessions that are usually limited in number and duration because of the availability of therapists and cost. Moreover, it is usually difficult to assess the degree of impairment at the beginning of the therapy and to quantify the benefits of the treatments due to the lack of objective measurement techniques.
Robotic devices have the potential to improve this situation. An intelligent robot mechanically coupled with the arm of the patient can be used to help the patient carrying out exercises during the rehabilitation period, thus increasing the time spent in rehabilitation training. Moreover, the sensors of the robot can be used to asses the degree of the impairment at the beginning of the therapy cycle and to monitor the progresses.
In fact, a number of robotic devices have been developed in the past years for both academic and commercial purposes. For example, a 7 DoF powered upper limb exoskeleton has been developed at University of Washington, Seattle, USA as a rehabilitation/assistive device to tackle dysfunctions involving a loss of force in the upper limb. Researchers at Scuola Superiore Sant'Anna, Pisa, Italy developed the MEMOS system, a low cost 2 degrees of freedom Cartesian robot for motor recovery of upper limb after Stroke. The ACT 3D system has been developed at North-western University, USA, to create a virtual world for arm movement training during grasping and releasing tasks.
The research in academic environments has also generated a small number of commercial devices. For example, the MIT-Manus developed in the framework of academic research at MIT, Boston, USA and subsequently patented (U.S. Pat. No. 5,466,213 (1995)) is now commercialized by Interactive Motion Technology, USA, as the InMotion 1,2,3 devices for use in rehabilitation of shoulder, elbow and wrist.
Similarly, there is a number of patents submitted in the field. For example, Erlandson (U.S. Pat. No. 4,936,299 (1990)) describes an apparatus and method for rehabilitation that takes advantage of a robotic arm controlled by a CPU. Baker (patent No. CA 2 244 358 (2000)) describes a therapeutic wrist rotator for the rehabilitation of the wrist. Reinkensmeyer et al. (U.S. Pat. No. 6,613,000 (2003)) describe a computer based system that provides arm movement therapy for patients with sensory impairments that can operate over the World Wide Web and provide personalized programs of therapeutic exercise. Diaz et al. (U.S. Pat. No. 2005/0273022 A1 (2005)) describe a portable medical device for joint rehabilitation by means of continuous passive motion. Dewald et al. (U.S. Pat. No. 2007/0066918 A1 (2007)) describe a system for the rehabilitation of gravity-induced limbs coordination dysfunction after stroke or other neurological disorders.
Results from study and clinical trials conducted with robots such as the MIT-Manus show that the robotic mediated approach is safe, well accepted by patients and useful (see for example Krebs et al., Technol. Health Care 7, 6 (December 1999), 419-423).
However, the present generation of rehabilitation robots still presents several unsolved issues that prevent it from being used on a large scale. Among them, cost is an important one. The robotic device should be cheap enough to be widely adopted by care centers. Simplicity of use is also an issue in case the robotic device has to be used at home by the patients. The “use-at-home” feature asks also for portability of the device.
In fact, the devices and/or patents previously described can be roughly classified into two categories: (1) expensive and non-portable devices that can be used to implement a number of different rehabilitation programs given their complex structure; (2) simpler, more specialized devices that can be used for a restricted number of rehabilitation programs.
Several patents have been issued for such specialised devices. For example, US Pat. No. 2007/0021692 describes a system for performing induced limb movements. Hand or foot trajectories are recorded by means of position sensors, and the pressure exerted by the limb can be recorded.
WO Pat. No 99/61110 describes a system for the training of quick reach movements (feed forward movements). The system incorporates position measurement (hand, arm, joints), EMG measurement and feedback to the user.
U.S. Pat. No. 7,311,643 describes a portable upper limb and shoulder exercise board. It provides means to move a handle in a plane with a discretely variable friction coefficient.
JP Pat. No 2007185325 describes a system to perform reaching exercises on a table. The system is portable and provides means for measuring the position of a grip used by the subject and for measuring the force action on the grip. The position of the grip does not provide information on the configuration of the arm.
JP Pat. No. 2002272795 describes an upper limb rehabilitation device that includes a measurement of position and force exerted by the user on grip (transportation device), and feedback means. The system requires an instrumented table with tracks over which the transportation device can move.
JP Pat. No. 2004008605 describes a limb rehabilitation training apparatus. It provides means to measure the force exerted by a limb on a fixed device together with means to provide feedback to the user, such as video, sound, vibration).
It is an object of the invention to provide a simple and cost effective device enabling the user to conduct reaching movements in a large workspace